Chemical composition of shells from red (Strongylocentrotus franciscanus) and green (Strongylocentrotus droebachiensis) sea urchin

► Shells of sea urchins constitute 40.7-77.9% of the total body weight. ► Naphthoquinone was present in both green and red sea urchin shell extracts. ► Shells of sea urchins contain spinochromes. ► Colour of sea urchin shells is influenced by different amounts of the same pigments.